Equivalent Air Depth question

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Mr. Dooley

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The formula makes sense to me so no issues there. Curious about its usage. I know EAD is handy if you're diving EAN and using dive tables.

But do people also use EAD for nitrogen narcosis management? If from a nitrogen narcosis standpoint I'm comfortable diving air to 100', I'd have the same PN2 diving EAN 30 to 120' while not exceeding the mix's MOD (assuming a PO2 no greater than 1.4).

Makes intuitive sense to me but I know there could be other factors - narcotic effects of oxygen, etc. With trimix I know there's a formula for Equivalent Narcotic Depth which does treat O2 as being equally narcotic as N2 for safety reasons. Beyond that I haven't dug too much into END as I'm not diving trimix.
 
Why would you keep O2 out of the narcosis management?

Makes sense to factor in everything of course. I just recall that during OW training it's bashed into you the N2 is the narcotic agent, and the primary O2 concern (from a mix standpoint) is not exceeding 1.4 basically. In my technical training materials the additional O2 considerations emphasized are about toxicity - CNS clock, OTUs, etc. While it's mentioned that O2 can be narcotic it don't recall the material going too deep into that.

There is no benefit or narcosis reduction diving EAN mixes. It is used when diving He mixes.

So this would suggest (if I'm reading correctly) that O2 is equally narcotic as N2, otherwise wouldn't there be a benefit from reducing the partial pressure of the more narcotic component?

This is all very interesting to me. I feel the way nitrogen narcosis was taught about in OW training is completely at odds with the idea of N2 and O2 being equally narcotic (which if they are then I can see why EAD wouldn't have any bearing on narcosis management).
 
You narcosis will most likely be worse using nitrox as you extend your bottom time, if you believe O2 to be equally narcotic.
 
Makes sense to factor in everything of course. I just recall that during OW training it's bashed into you the N2 is the narcotic agent, and the primary O2 concern (from a mix standpoint) is not exceeding 1.4 basically. In my technical training materials the additional O2 considerations emphasized are about toxicity - CNS clock, OTUs, etc. While it's mentioned that O2 can be narcotic it don't recall the material going too deep into that.
Yes, I know in OW they tend to speak more about N2 narcosis, I don't know why they do it, but it isn't really right.

My guess: in the rec realm, you want to reduce decompression stress as much as possible; to do that, increasing the O2 in the mix is the key. If people start mentioning that O2 is as narcotic as nitrogen, that may make people think that O2 is too risky, they wouldn't dive nitrox, then would maybe dive less...

So this would suggest (if I'm reading correctly) that O2 is equally narcotic as N2, otherwise wouldn't there be a benefit from reducing the partial pressure of the more narcotic component?
It isn't as narcotic as nitrogen, because narcotic power is very complicated to measure; actually, some clues suggest that it is more narcotic than nitrogen... There are some hints that narcotic power is related to the solubility of gases into lipids, but science isn't really sure right now.

However, the table in Wikipedia posted by @Ucarkus gives some good clues.

This is all very interesting to me. I feel the way nitrogen narcosis was taught about in OW training is completely at odds with the idea of N2 and O2 being equally narcotic (which if they are then I can see why EAD wouldn't have any bearing on narcosis management).
Again, O2 and N2 are not narcotic to the same point, O2 is slightly more narcotic.
 
The formula makes sense to me so no issues there. Curious about its usage. I know EAD is handy if you're diving EAN and using dive tables.

But do people also use EAD for nitrogen narcosis management? If from a nitrogen narcosis standpoint I'm comfortable diving air to 100', I'd have the same PN2 diving EAN 30 to 120' while not exceeding the mix's MOD (assuming a PO2 no greater than 1.4).

Makes intuitive sense to me but I know there could be other factors - narcotic effects of oxygen, etc. With trimix I know there's a formula for Equivalent Narcotic Depth which does treat O2 as being equally narcotic as N2 for safety reasons. Beyond that I haven't dug too much into END as I'm not diving trimix.
O2 is considered comparably narcotic to N2.

END/EAD is not really used in nitrox diving anymore since most people aren't diving air tables, but the formulas as you alluded to are important in trimix.
 
In the old days it was thought that just Nitrogen was narcotic. Even the early days of Nitrox it was claimed that the O2 helped with the Narcotic effect. Some old school shops will still sell that line.

But times have changed. Now that Nitrox has been used a lot more and is more understood it has been found that there isn't a difference. O2 is just as narcotic as Nitrogen. I have even herd that it is ever so slightly more as well, but can't find that source again.

The only way to back off the narcotic effect is add a light gas. Helium does the job. I have also seen someplace that Hydrogen works as well, but making a safe diving mix is a problem. That hydrogen really wants to bond with the oxygen, makes great fire, heat, boom. So Helium it is.
 
The only way to back off the narcotic effect is add a light gas. Helium does the job. I have also seen someplace that Hydrogen works as well, but making a safe diving mix is a problem. That hydrogen really wants to bond with the oxygen, makes great fire, heat, boom. So Helium it is.
Read somewhere that hydrogen does work (hydrolox) (sp?) but it has to have a very low oxygen content of less than 4%, circa 300m/1000ft.
 

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